The present invention relates generally to dual-action tools and, more particularly, to a motor driven dual-action tool whereby the tool is provided with the ability to switch between axial motion functions smoothly and uninterruptedly, such as between heavy grinding rotary action and random orbital sanding action without powering down the tool and without any mechanical manipulation by the user.
The background information discussed below is presented to better illustrate the novelty and usefulness of the present invention. This background information is not admitted prior art.
A sander is a power tool generally used to smooth rough surfaces. Woodworking sanders are usually operated by electrical power, while the sanders used in auto-body repair are powered by compressed air.
Circular (also referred to as rotary) motion sanders are used for different operational functions. One use is where the motor drive imparts a continuous, high speed, simple rotary action to a backup pad fitted with a sanding or grinding disc. This form of operation is used in the heavy sanding or grinding of various materials, such as in the grinding of welds and metals used in automobile bodies.
The random orbital motion of random orbital sanders is produced by simultaneously spinning the sanding disk and moving it in an ellipse. This motion is produced by the eccentric relationship between the backup pad and the drive shaft and ensures that no single part of the abrasive material travels the same path twice. Random orbital sanders approach the speed and aggressiveness of a belt sander, while producing a finish finer than that available from a standard, slow speed, orbital finishing sander. Because of its unique random sanding action, this sander does not leave swirl marks, and it is not sensitive to the direction of the wood grain. This makes the sander especially useful for sanding two pieces of wood that meet at right angles. Random-orbit sanders use sandpaper disks and many random-orbit sanders now come with dust collectors. Random orbital sanding provides for surface preparation for finishing with paint, stain or other type final appearance.
In the past, a finisher had to use both types of sander to accomplish the job. First a rotary machine would be utilized to provide high speed grinding to cut through heavy paint, welds, and metal and then a random orbital machine is brought into play to smooth out the deep scratch marks from the previous grinding operation. Using this method was labor intensive, time consuming, and requires investing in and maintaining a two tools.
To provide for a single tool that would provide both rotary and random orbital motions, a double acting sanding tool became available. Although an improvement, this tool required its user to interrupt the sanding or grinding operation in order to mechanically manipulate the tool to change the type of action. Although this tool presented an improvement in the art, if required a user to take the time and effort to stop the tool completely in order to make the mechanical adjustments required to use the tool for an alternative function before the tool can be restarted. A succeeding improvement provided for a single tool that could perform both rotary and random orbital motion by providing a clutch assembly that allows an operator to switch the function of the apparatus from random orbital sanding to rotary grinding